SOAN 2120 Chapter Notes - Chapter 7: Factorial Experiment, Blind Experiment, European Credit Transfer And Accumulation System

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Chapter 7: Experimental Research – page #168-191:
Experimental research builds on the principals of a positivist approach more directly than do
the other research techniques
Researchers in the natural sciences, related applied fields, and the social sciences conduct
The experiment’s base logic extends commonsense thinking commonsense experiments
are less careful or systematic than scientifically based experiments
In commonsense language, an experiment is when you modify something in a situation, then
compare an outcome for what existed without modification
Three things researchers do in experiments:
1. Begin with a hypothesis
2. Modify something in a situation
3. Compare outcomes with and without the modification
Compared to the other social research techniques, experimental research is the strongest for
testing causal relationships because the three conditions for causality (temporal order,
association, and no alternative explanations) are best met in experimental designs
Research Questions Appropriate for an Experiment:
The Issue of an Appropriate Technique:
The match between a research question and technique is not fixed but depends on informed
You can develop judgment from reading research reports, understanding the strengths and
weaknesses of different techniques, assisting more experienced researchers with their
research, and gaining practical experience
Research Questions for Experimental Research:
The experiment allows a researcher to focus sharply on causal relations, and it has practical
advantages over other techniques, but is also had limitations
The questions appropriate for using an experimental logic confront ethical and practical
limitations of intervening in human affairs for research purposes
The pure logic of an experiment has an experimenter intervene or induce a change in some
focused part of social life, then examine the consequences that result from the change or
intervention this usually means that the experiment is limited to research questions in which
a researcher is able to manipulate conditions
Experimenters are highly creative in simulating such interventions or conditions, but they
cannot manipulate many of the variables of interest to fit the pure experimental logic
The experiment is usually best for issues that have a narrow scope or scale this strength
allows experimenters to assemble and “run” many experiments with limited resources in a
short period
In general, the experiment is better suited for micro-level (e.g., individual or small-group
phenomena) than for macro-level concerns or questions
Experiments encourage researchers to isolate and target the impact that arises from one or a
few causal variables the strength in demonstrating causal effects is a limitation in situations
where a researcher tries to examine numerous variables simultaneously
Random Assignment:
Random assignment facilitates comparison in experiments by creating similar groups
Why Randomly Assign?
Random assignment is a method for assigning cases to groups for the purpose of making
comparisons it is a way to divide or sort a collection of cases into two or more groups in
order to increase one’s confidence that the groups do not differ in a systematic way
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It is a mechanical method; the assignment is automatic, and the researcher cannot make
assignments on the basis of personal preference or the features of specific cases
In everyday speech, random means unplanned, haphazard, or accidental, but it has a
specialized meaning in mathematics in probability theory, random describes a process in
which each case has a known chance of being selected
Random selection lets a researcher calculate the odds that a specific case will be sorted into
one group over another
Random means a case has an exactly equal chance of ending up in one or the other group
Although the process itself is entirely due to chance and does not allow predicting a specific
outcome at one specific time, it obeys mathematical laws that makes very accurate
predictions possible when conducted over a large number of situations
Random assignment or randomization is unbiased because a researcher’s desire to confirm
a hypothesis or a research subject’s personal interests do not enter into the selection process
Unbiased does not mean that groups with identical characteristics are selected in each
specific situation of random assignment instead, it says that the probability of selecting a
case can be mathematically determined, and, in the long run, the groups will be identical
Sampling and random assignment are processes of selecting cases for inclusion in a study
How To Randomly Assign:
A researcher begins with a collection of cases, then divides it into two or more groups by a
random process, such as asking people to count off, tossing a coin, or throwing a dice
A random method is writing each persons name on a slip of paper, putting the slips in a hat,
mixing the slips with eyes closed, then drawing the first 16 names for group 1 and the second
16 for group 2
Matching vs. Random Assignment:
Some researchers match cases in groups on certain characteristics, such as age and sex
matching is an alternative to random assignment, but it is an infrequently used one
Matching presents a problem: what are the relevant characteristics to match on, and can one
locate exact matches? Individual cases differ in thousands of ways, and the researcher
cannot know which might be relevant
True matching soon becomes an impossible task
Experimental Design Logic:
The Language of Experiments:
Experimental research has its own language or set of terms and concepts random
assignment and independent and dependent variables
In experimental research, the cases or people used in research projects and on whom
variables are measured are called the subjects
Parts of the Experiment:
We can divide the experiment into 7 parts the following 7 make up a true experiments:
1. Treatment or independent variable what the researcher modifies; it is the independent
variable or a combination of independent variables
2. Dependent variablethe physical conditions, social behaviours, attitudes, feelings, or
beliefs of subjects that change in response to a treatment; can be measured by paper-
and-pencil indicators, observation, interviews, or physiological responses
3. Pretest the measurement of the dependent variable prior to introduction of the
4. Posttest the measurement of the dependent variable after the treatment has been
introduced into the experimental situation
5. Experimental group the group that receives the treatment or in which the treatment is
6. Control group the group that does not receive the treatment
7. Random assignment -
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